Reactivity of Tantalum/Iridium and Hafnium/Iridium Alkyl Hydrides with Alkyl Lithium Reagents: Nucleophilic Addition, Alpha-H Abstraction, or Hydride Deprotonation?

Abstract

Cp*IrH 4 reacts with Hf(Np) 4 (Np = CH 2 C(CH 3 ) 3 ) to yield the heterobimetallic complex [Hf(Np) 3 (μ-H) 3 IrCp*], 2. Treatment of 2 with neopentyl lithium (NpLi) results in the nucleophilic addition of a neopentyl moiety onto the Hf center, restoring Hf(Np) 4 and displacing the Cp*IrH 3 iridate fragment. By contrast, treatment of the tantalum/iridium analogue, [Ta(Np) 3 IrH 2 (Cp*)], 1, with NpLi triggers the α-hydrogen abstraction at a Ta-neopentyl moiety and leads to the formation of the alkylidene -ate complex [Li][{Ta(CH t Bu)(Np) 2 }{IrH 2 Cp*}], 4. The benzylidene analogue, [K][{Ta(CHPh)(Np) 2 }{IrH 2 Cp*}], 5, is obtained upon reacting 1 with benzyl potassium. An unusual vinyl oxo species, [{Li(THF) 3 }Ta(O)(Np) 2 {μ-C 2 H 3 }IrH(Cp*)], 6, is formed when the reaction of 1 with NpLi is carried out in THF, due to THF fragmentation.

Diverse Thermal and Photochemical Reactivity of an Al–Fe Bonded Heterobimetallic Complex

“…In this case, our results show that C–O activation chemistry of 1 is not restricted only to weak C–O bonds. This behavior complements behavior of other bimetallic systems toward THF − and expands the diversity of outcomes available from binuclear mechanisms.…”

A versatile strategy for the formation of hydride-bridged actinide–iridium multimetallics

“…† The uranium species 1 crystallizes in the space group C2/c, with two of the iridium centers generated through symmetry, and co-Scheme 1 Previously reported syntheses of reactive multimetallic complexes from IrCp*H 4 . 40,43,[49][50][51] Scheme 2 Synthesis of 1 and 2.…”

“…40,42 Promisingly, Hou and coworkers had also previously demonstrated the ability to form hydride-supported lanthanide-iridium bimetallic complexes of ytterbium, dysprosium, and lutetium in high yields. 40,43,49,50,51 Previous efforts towards the formation of iridium-metal bonds with IrCp*H 4 have primarily focused on protonolysis pathways, which are typically dependent on metal-alkyl or metal-aryl species as starting materials. 40,41,43,49,50 Due to the greater prevalence and variety of actinide-halide starting materials, the previously reported, closely-related potassium iridate species K[IrCp*H 3 ] was targeted for the formation of An-Ir multimetallic species via salt-elimination pathways.…”

“…40,43,49,50,51 Previous efforts towards the formation of iridium-metal bonds with IrCp*H 4 have primarily focused on protonolysis pathways, which are typically dependent on metal-alkyl or metal-aryl species as starting materials. 40,41,43,49,50 Due to the greater prevalence and variety of actinide-halide starting materials, the previously reported, closely-related potassium iridate species K[IrCp*H 3 ] was targeted for the formation of An-Ir multimetallic species via salt-elimination pathways. 49 Here, we report joint efforts from the Arnold and Camp groups to synthesize uranium-and thorium-iridium multimetallic species via salt-elimination reactions between U(IV)/Th(IV) halides and K[IrCp*H 3 ] with unique actinide-iridium interactions.…”

“…48 The pentamethylcyclopentadienyl (Cp*) iridium polyhydride species IrCp*H 4 has demonstrated the ability to form highly reactive complexes when paired with other metal species (Scheme 1). For instance, Camp and coworkers showed that when reacted with several isobutylaluminum derivatives, 43,49 the resulting iridium aluminum complexes promote cooperative heteroallene cleavage, while reactions with group 4 and group 5 neopentylidene species 40,50 led to hafnium-and tantalum-iridium complexes that facilitate H/D exchange. 40,42 Promisingly, Hou and coworkers had also previously demonstrated the ability to form hydride-supported lanthanide-iridium bimetallic complexes of ytterbium, dysprosium, and lutetium in high yields.…”